Race against time to prevent meltdown of nuclear reactor
Crisis began when quake knocked out all power
The nuclear power plant at Fukushima was thrown into crisis when the earthquake knocked out all power from its systems.
Officials were working desperately last night to contain a dangerous build-up of radioactive gases after the reactor's core began to overheat.
The Japanese military was called in and US Air Force pilots were scrambled to deliver a specialist coolant to the stricken reactor. With the plant unable to generate the power needed to pump water around the system, its fuel rods became increasingly unstable and the Japanese government was forced to concede that a radiation leak was possible.
Its nuclear safety agency said the build-up of pressure, to 1.5 times the normal level, meant their only option could be to release some radioactive steam in order to prevent a larger nuclear accident.
They insisted that the move would not affect human health. But thousands of residents in the surrounding areas were evacuated as a precaution.
While officials insisted there was no danger of the reactor exploding, a failure in the cooling system could lead to an accident similar to Three Mile Island in the United States in 1979, when dangerous radioactive gases were released into the atmosphere following a cooling-system failure.
One expert warned there was the possibility of a core meltdown, which would have devastating effects for millions of people and the environment.
As officials at Fukushima battled to contain the rising temperatures, a spokesman for Tokyo Electric Power, which runs the Fukushima plant, said: "Pressure has risen in the container of the reactor and we are trying to deal with it."
The Japanese government dispatched 160 military personnel to the nuclear plant to assess the situation and provide any assistance needed.
But there were warnings that once a core meltdown began there would be little anyone could do to prevent radioactive material escaping. One of the main fears was the danger of what has been dubbed the 'China Syndrome', where the rods in the core reach such a critical temperature that they melt through the floor of the reactor and radiation contaminates the water table and wider environment.
James Acton, a physicist who examined Japan's Kashiwazaki nuclear plant after a 2007 earthquake, said: "If they can't restore power to the plant (and cool the reactor), there's the possibility of some sort of core meltdown."
Yuji Kakizaki, an official at Japan's nuclear safety agency, said that plant workers were cooling the reactor with a secondary cooling system, which was less effective than the regular cooling method.
But Sue Ion, the former chief technology officer for British Nuclear Fuels, said there was no need to panic and said the Japanese authorities were managing the situation well.
"They have had an issue about restarting their diesel generators. They will probably have to release some radioactive steam, but nothing that is over and above normal procedures." ( © Daily Telegraph, London)